Question

The metal of group 2 from top to bottom are Be, Mg, Ca, Sr, and Ba.
(1) Which of these elements will form ions most readily and why?
(2) State the common feature in the electronic configuration of all these elements.

Answer 1

Hint: As we move down the group the size of the atom will increase. This means that the electrons are far apart from the nucleus thereby having relatively weak force of attraction. As the electrons are far apart, they can eject with less energy.

Complete step by step answer:
The group 2 elements also called the alkaline earth metals consist of beryllium, magnesium, calcium, barium, strontium and radium and are soft, silver metals that are less metallic in nature than the Group 1 alkali metals.
Although many characteristics are common throughout the group, the heavier metals such as Sr, Ba, and Ra are as reactive as group 1 alkali metals. Let us discuss the trend of alkaline earth metals:
Beryllium is the least reactive and does not react with water even at high temperatures. However, magnesium reacts reasonably with steam, calcium and strontium readily react with moist air.

(1) We observe that as we move down the group the ionization energy decreases. This is because the number of shells increases down the group and the valent shell is far apart from the nucleus. Hence barium will form ions most readily due to large size and low ionization energy.

(2) When we write the electronic configuration of group 2 elements, we observe that all the elements have 2 electrons in their last or valent shell. Hence all the elements of group 2 have a valency of 2, i.e. they lose 2 electrons to gain maximum stability (completion of octet).

Note:Although the elements of group 2 have valency of 2, Be has properties similar to that of the element to its diagonal i.e. aluminium (Al). The oxides of beryllium as well as aluminium are hard and have high melting points which is not observed in other oxides of group 2 elements. Along with that beryllium is not readily attacked by acids like aluminium as they form an oxide layer on the surface.